Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; Heilongjiang Bayi Agricultural University, Daqing 163319, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Environ Pollut. 2018 Nov;242(Pt A):82-89. doi: 10.1016/j.envpol.2018.06.088. Epub 2018 Jun 27.
Nitrogen (N) enrichment has great consequences on several fundamental ecological processes through its impacts on plant nutrition traits (i.e. nutrient concentration and stoichiometric ratios); however, the extent to which the effects of N enrichment depend on phosphorus (P) availability are less well understood. While there is mounting evidence for the species-specific responses of plant nutrition traits to nutrient enrichment, we know little about the changes at the community-level. Here, we measured community-level biomass weighted (CWM) and non-weighted (CM) plant N and P concentrations and N:P ratio in a temperate meadow steppe after four years factorial N and P addition, with biomass and nutrition traits of each species in each plot being recorded. Nitrogen addition significantly increased community-level N concentration, decreased P concentration, and enhanced community N:P ratio. Phosphorus addition had no impacts on community-level N concentration, significantly increased P concentration, and reduced community N:P ratio. The impacts of N addition on community nutrition traits were not dependent on P addition and the community-level nutrition trait responses to N and P additions were primarily driven by intraspecific trait variation (ITV) rather than by species turnover. Community-level nutrition traits in the temperate meadow steppe were sensitive to the projected N and P enrichment. While nutrient enrichment had substantially changed community composition, its impacts on community nutrition traits were driven by ITV. Nitrogen deposition would result in imbalance of N and P in plant community, as indicated by the substantial increase in community-level N:P, which was not affected by increased P availability.
氮（N）富集通过影响植物营养特性（即养分浓度和化学计量比）对许多基本生态过程产生重大影响；然而，氮富集的影响在多大程度上取决于磷（P）的可用性还不太清楚。虽然有越来越多的证据表明植物营养特性对养分富集具有特定物种的响应，但我们对群落水平的变化知之甚少。在这里，我们在经过四年的 N 和 P 加富因子处理后，测量了温带草甸草原的群落水平加权（CWM）和非加权（CM）植物 N 和 P 浓度以及 N:P 比，记录了每个样地中每个物种的生物量和营养特性。氮添加显著增加了群落水平的 N 浓度，降低了 P 浓度，并提高了群落 N:P 比。磷添加对群落水平的 N 浓度没有影响，显著增加了 P 浓度，并降低了群落 N:P 比。氮添加对群落营养特性的影响不依赖于磷添加，氮和磷添加对群落营养特性的响应主要由种内变异（ITV）驱动，而不是由物种更替驱动。温带草甸草原的群落营养特性对预计的 N 和 P 富集会很敏感。虽然养分富集已经大大改变了群落组成，但对群落营养特性的影响是由 ITV 驱动的。氮沉降会导致植物群落中 N 和 P 的失衡，如群落水平 N:P 的大幅增加所示，而增加 P 的可用性并没有影响到这一点。
